Laboratory Investigation of the Effect of Slenderness Effect on the Non-Darcy Groundwater Flow Characteristics in Bimsoils

Abstract

A series of experimental flow tests for artificial block-in-matrix-soils (bimsoils) samples with various slenderness ratios were performed to study the Non-Darcy groundwater flow characteristics. The variations of seepage velocity, permeability coefficient, critical sample height, and non-Darcy flow factor for samples against slenderness ratios were investigated. A servo-controlled flow testing system that was developed by the authors was adopted to conduct the flow test. Cylindrical bimsoil samples (50 mm diameter and various heights) with staggered rock block percentages (RBPs) (30, 40, 50, and 60%, by mass) were prepared by compaction tests to roughly insure the same porosity of the soil matrix. The testing results show that flow the distance has a strong influence on the flow characteristics of bimsoil, and the relationship between the permeability coefficient and slenderness ratio is proposed. In addition, the critical sample height to eliminate the slenderness effect was determined, and the relationship between the critical sample height and RBP was established. Moreover, the responses of non-Darcy flow were studied by using an index of non-Darcy βfactor, which reveals the internal mechanism of the effect of flow distance on groundwater flow characteristics. The research results can be useful to the prediction of flow piping disaster for geological body made up of bimsoils.

Editorial of Special Issue “Advances in Groundwater Flow and Solute Transport: Pushing the Hidden Boundary”

“…In terms of non-Darcian flow, Wang et al [4] has conducted a series of experimental flow tests for bimsoils with various slenderness ratios. This study stated that the sample height had a strong influence on the flow characteristics of bimsoils, and the degree of non-Darcy flow decreased with the increase of sample height.…”

“…Also focusing on the experimental work of non-Darcian flow, like Wang et al [4], Chen et al [2] has conducted flow tests in synthetic single smooth and rough fractures. This study showed that non-Darcian Forchheimer flow was evident in both smooth and rough fractures, and it showed that the non-Darcian coefficient β c in the Forchheimer equation was most relevant for characterizing the heterogeneity of the rough single fractures.…”

On the effect of confining pressure on fatigue failure of block‐in‐matrix soils exposed to multistage cyclic triaxial loads

“…Recently, the studies on the fatigue behaviors of bimsoil have drawn engineers' attentions for the purpose of design and constructions. [8][9][10] Although detailed investigations have been performed on bimsoil via in situ testing, 11,12 laboratory compression test, 13 laboratory shear, 14 laboratory tension test, 15 or numerical tests, 16 mesoscopic testing using real-time acoustic emission and in situ CT scanning testing. 2,17 Most of the studies focused on the static loading paths.…”

Simple Fully Automatic Testing Method of Seepage Indices for Low-Permeability Materials

“…As a result, indoor tests represent the primary testing method of seepage indices for low-permeability materials. The indoor seepage testing methods for low-permeability materials have mainly evolved from the testing methods for high-permeability materials, including the anti-seepage grade measurement method of concrete [21,22], improved triaxial methods for seepage testing [23,24], and improved conventional methods for seepage testing [25][26][27][28]. These methods allowed upgrading the testing ability of seepage indices for low-permeability materials and promoted their engineering application.…”

“…However, the seepage flux had to be measured manually with a volume change tube by operating mechanical buttons [25]. In research on the slenderness influence of bimsoils on non-Darcy groundwater flow characteristics, a servo-controlled flux testing system was developed, but the seepage flux was still measured manually using a cylinder [26]. A pressure difference sensor helped build an experimental system for the permeability measurement of matrix particles of shale under a pore pressure up to 8 MPa, but the devices and the experimental process were complicated [27].…”